Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSHONDA2002CIVIC SIREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 141 (IDLE CONTROL SYSTEM)ALTERNATOR FR SIGNAL CIRCUIT TROUBLESHOOTING

2002 Honda Civic Si

Alternator FR Signal Circuit Troubleshooting

2002 Honda Civic SiSECTION Alternator FR Signal Circuit Troubleshooting

WARNING: This page is about a different car, the 2006 Honda Odyssey and 2005 Honda Odyssey. However, it is still accessible from the selected car via links, so may be relevant.

Start the engine, and let it idle.
Monitor the ALTERNATOR in the DATA LIST with the HDS.
Check if the indicated percentage varies when the headlight switch is turned on.
Does the percentage vary?
1. YES - The alternator signal circuit is OK.
2. NO - Go to step 4.
Turn the headlight switch and ignition switch OFF.
Jump the SCS line with the HDS.
Disconnect the alternator 4P connector.
Disconnect PCM connector C (44P).
Check for continuity between body ground and PCM connector terminal C41.

Fig 1: Checking Continuity Between Body Ground And PCM Connector Terminal C41
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Repair short in the wire between the PCM (C41) and the alternator.
2. NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM (see PCM UPDATING AND SUBSTITUTION FOR TESTING ), then recheck. If the symptom/ indication goes away with a known-good PCM, replace the original PCM (see PCM REPLACEMENT ).

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.